XDM
1) For now, 40 S&W only.
2) New grips are sharper, but less comfortable, and grip tape is $7.
3) Match grade barrel will improve "competition" accuracy by a small percentage, but my standard XDs already produce "which eye?" accuracy at defensive distances.
4) The adjustable backstraps only go SMALLER than the standard XD, which is border-line small as is for me.
5) The capcity is irrelevant, unless again, it's for competition.

Competition Gun? Buy the XDM.
Defensive Gun? Buy the XD9SC, or the XD45C. Easier to conceal.